Field of the Invention
The present invention relates to a vehicular seat element.
Description of the Prior Art
Passenger seats in vehicles, such as automobiles, are typically fabricated from a foam (usually polyurethane) material which is molded into the desired shape and covered with an appropriate trim cover. The foamed material is selected to provide passenger comfort by providing a resilient seat and the trim cover is selected to provide the desired aesthetic properties.
Conventional vehicular seats are typically manufacture from polyurethane foam, in particular high resiliency (HR) polyurethane foam. Typical HR polyurethane foam has an impact resilience (i.e., ball rebound) greater than 50%. Further, typical HR polyurethane foam is also generally taken to encompass the foams known as cold-cure foam.
HR molded foams offer several advantages. First, the typically possess a support factor (ratio of 65% IFD to 25% IFD) that is superior to that of conventional slab or hot-molded foams. Second, the amount of energy required to accelerate foam cure and develop final properties is less. Third, HR molded foams can be formulated to meet the requirements of various small-scale flammability tests.
Designers of vehicular seats conventionally select a specification profile generally near the 50th percentile of weight and size of male passengers who occupy the seats. Practically, this means that most commercially available vehicular seats have specification profile that achieves a target comfort for a person who weighs approximately 175 pounds (79.5 kilograms) and is approximately 5 feet, 11 inches (180.3 cm) tall.
One parameter of target comfort for designers of vehicular seats is the so-called “under-thigh” portion of the seating surface. This portion of the seating surface is important since pressure applied to the under-thigh portion of the seat occupant can negatively affect blood flow leading to discomfort of the seat occupant.
A problem associated with selection a specification profile generally near the 50th percentile of weight and size of passengers who occupy the seats is that a significant portion of vehicular passengers do not weigh approximately 175 pounds (79.5 kilograms) and/or are not approximately 5 feet, 11 inches (180.3 cm) tall—e.g., large individuals, tall individuals and a significant proportion of women and children. Thus, this significant portion of vehicular passengers are highly likely not to benefit from the target comfort associated with the specification profile for most commercially available vehicular seats. This problem is exacerbated by the fact the seat designers are typically constrained to use foam materials which have a substantially uniform specification profile across all operation temperatures of the vehicle (e.g., −40° to 85° C.)—e.g., HR polyurethane foam.
Thus, it would be highly desirable to have a vehicular seat element having a specification profile that proves a larger window of target comfort for this significant portion of vehicular passengers. For example, it would be highly desirable if the window of target comfort for a given vehicular seat element extended from 5th percentile to 95th percentile of weight and size of passengers who occupy the seats:
MaleFemaleHeight (cm/in)Weight (kg/lb)Height (cm/in)Weight (kg/lb) 5th163/64.063.50/140.0157/62.049.44/10950th173/68.079.15/174.5166/65.563.50/14095th183/72.097.30/214.5178/70.076.66/169
It would further highly desirable if such a larger window of target comfort was manifested, for example, in a reduction in pressure to the seat occupant in the area of the seating surface substantially corresponding to the under-thigh region of the occupant.